The modern grain threshing system of combines represents one of the most operationally complex and costly pieces of agricultural equipment. Its level of performance in accomplishing its functions can be profoundly influenced by a multitude of operator adjustments, many of which can be made during actual operation. The combine also encounters a wide range of harvesting situations and crop conditions. Because of these variables the potential for stalling the grain threshing system of the combine exists.
Stalling can occur when the combine encounters variables such as, intermittent high density of the crop, patches of weeds having exceedingly high moisture content, and ingestion of foreign obstacles such as rocks and pieces of wood. Rocks, wood, and other foreign obstacles are typically encountered when attempting to harvest crops which have been broken down by high winds, hail, and rain.
Previously used methods of preventing stalling in conventional threshing systems of combines includes slowing down the feed rate of material delivered to the threshing system by slowing down the feeder chain, reducing the forward speed of the combine, and reversing rotational direction of the threshing mechanism. These methods are relatively ineffective in maintaining productivity and efficiency. Therefore development of a more effective control system for the combine threshing system is desired.
One of the more recent developments in threshing systems is the rotating concave threshing system known in the art as a Bi-Rotor.TM. threshing system which utilizes a rotor positioned within a rotating concave. The construction of the rotating concave threshing system offers unique opportunities for preventing stalling, by providing a control system for monitoring the above listed factors to prevent stalling.
Although similar control systems have been designed for conventional grain threshing systems to improve performance, they have been relatively unsuccessful owing to the slow responsiveness of the system. This is caused by the large amount of kinetic energy generated by the conventional grain threshing systems in which the rotor turns and not the concave. However, the grain threshing system of this invention generates very low energy in the rotating concave and for the first time makes possible stall prevention control of high effectiveness. The present invention is directed to overcome one or more of the problems as set forth above.